1. Field of the Invention
The present invention is in the field of air conditioning and heating installations, and particularly relates to a bearing assembly for supporting the undriven end of a damper blade installed within an air duct or conduit.
2. The Prior Art
It is conventional in air conditioning and heating installations to provide in the various ducts or conduits a series of damper members which are typically adjusted so as to proportion the distribution of air within the system. The dampers generally are provided with a driven end, a. g. an end having a control shaft mounted in a fitting which may be adjusted by handle or motorized control. The opposite end of the blade is generally supported by a bearing component comprising a bracket adapted to be fixed to the blade and a projecting rod or pin adapted to extend through a bearing aperture formed in the duct or in a bearing fixture supported externally of the duct.
Mounting of the damper blade to the duct has generally involved passing the driven end or shaft affixed to the blade through an aperture formed in one wall of the duct, and thereafter inserting the blade to a position transversely of the duct and shifting the bearing pin into its bearing aperture coaxially located relative to the shaft mounting aperture.
As will be apparent from the foregoing description, if the blade provides a desirable close tolerance fit with the interior of the duct, the projecting bearing pin will interfere with the movement of the blade into the diametric position within the duct. In order to accommodate such positioning, it is conventional practice to supply a bearing pin which may be retracted against the force of a spring during the process of insertion and which will spring outwardly into the bearing aperture after the blade has been properly positioned. The degree of retractile movement necessary in a conventional duct installation is small due to the relatively inconsequential thickness of the duct, and it is necessary merely to retract the bearing pin an amount sufficient to clear such thickness.
Recently air conduit systems have been designed with pads or rolls of insulation affixed to the interior surface of ductware in order to improve the energy efficiency of the system. Since the insulation thickness is typically in the order of one inch or more, it will be apparent that a substantial retractile movement of the pin must be accommodated in order to permit the damper blade to be positioned within the duct.
Conventional damper bearing structures are incapable of the necessary retractile movement. Current installation techniques accordingly require that portions of the insulation be removed from the duct in line with the bearing aperture formed in the duct to provide clearance for bearing insertion. Obviously, the necessity for carving away insulation material, in addition to increasing the difficulties of installation, comprises to a degree the efficiency of the system and, in the case of air conditioning installations, leads to a situation wherein condensation forms on external metallic portions of the duct opposite the bare interior metal portions.